Measuring object distance using natural radiation emission - involves comparing intensities of measurement and reference beams, e.g. for autofocussing chambers

摘要

A method of determining the distance of an object using natural radiation emitted or reflected by the object involves limiting the extent of the radiation and dividing it into two defined beams whose intensities are evaluated. The measurement beam (M) is partially detected outside the focal plane by one channel and the reference beam (B), which contains the entire image intensity, is fully detected by a second channel. The distance is determined from the ratio of the reference intensity to the intensity difference. USE/ADVANTAGE - For simple, economical distance measurement, e.g. in autofocussing cameras.